Lysozyme (1,4-beta-N-acetylmuraminidase) is distributed in living tissue and is believed to play a role in defense against bacterial infections. (Fleming (1922) Proc Royal Soc London B39:306-317) Lysozyme functions by hydrolyzing polysaccharides in bacterial cell walls via a beta-glucosidase activity. The cell walls are thereby lysed, resulting in death of the cells. These enzymes act as bactericides, and this property explains their generalized presence in most of the biological fluids of mammals. For example, lysozyme is found, at various levels of concentration, in blood, tears, saliva, milk, etc., of mammals. It is also found in plants, e.g., in papaya. Lysozyme is present at high levels in hen egg white, from which it can be isolated relatively easily and with high purity. (Imoto et al. (1972) in The Enzymes (Boyer, P. D., ed) 3rd Ed, 7:665-668, Academic Press, Orlando, Fla.)
Lysozyme is added to cheese, sausage and marine products for preservation purposes and is also used as a medicinal agent, for example, in hemostatic, anti-inflammation, or tissue regeneration applications. It can also be used to preserve milk components for pediatric use. (Japanese Patent No. 16780/70, 1970) In biotechnology applications, lysozyme may be added to a bacterial culture during recovery of expressed protein, facilitating release of protein from the cells. (Zukaite et al. (2000) Lett Appl Microbiol 30:203-206)
Lysozyme derived from hen egg white can induce an allergenic response in sensitive individuals, thus limiting its use in certain applications such as food preservation. There is a need for new enzymes with microbial lysis activity as an alternative to hen egg white lysozyme.